Treatment of rubber



Patented Feb. 6, 1934 UNITED STATES PATENT OFFICE TREATMENT OF RUBBER William P. ter Horst, Akron, Ohio, assignor to The Naugatuck Chemical Company, Naugatuck, Conn, a corporation of Connecticut 16 Claims.

This invention relates to the treatment of rubher and similar vulcanizable materials, more particularly to treatment of the same with certain derivatives of reaction products of secondary aromatic amino compounds and aliphatic ketones. The invention also relates to the products of such treatment.

This case is a division of case Serial No. 488,560, filed Got. 13, 1930.

An object of this invention is to provide materials having the property of retarding the deterioration of rubber. Another object is to provide materials having the property of improving the resistance of rubber to abrasion. Other objects will be apparent from the following detailed description.

Reaction products of secondary amino compounds and aliphatic ketones may be prepared by reacting the amino compound and the ketone either with or without the aid of a suitable catalytic dehydrating agent. By this is meant that high molecular weight ketones and amines of high boiling point do not require the use of catalysts for economic production of reaction products, but that with low boiling amines and ketones the reaction products cannot be prepared economically without the use of a suitable catalytic agent. Examples of products within this invention are the reaction products of acetone and diphenylamine, acetone and phenyl alphanaphthylamine, acetone and phenyl betanaphthylamine, acetone and diphenyl ethylene diamine, acetone and mono ethyl aniline, methyl ethyl ketone and phenyl alpha-naphthylamine,

" mesityl oxide and phenyl alpha-naphthylamine,

acetone and diphenyl formamidine, mesityl oxide and phenyl beta-naphthylamine, acetone and diortho tolyl guanidine, acetone and diphenyl guanidine, acetone and p-p' di (naphthylamino) diphenyl methane, acetone and ortho tolyl biguanide. Their preparation is illustrated by the following procedures:

Example A.--The reaction between acetone and diphenyl amine is preferably carried out at relatively high temperatures and high pressures in the presence of a dehyration agent, such as iodine, which also has a catalytic efiect on the reaction. The amount of acetone may vary from one to three moles per mole of diphenylamine. For example 320 pounds of diphenylamine, 220

pounds of acetone, 600 grams of iodine are heated during 20 hours at approximately 220 C. The pressure is approximately 600 pounds per square inch at this temperature. An iron autoclave may be used with or without agitation. At the end of about 20 hours the contents are cooled and the excess acetone and water formed are distilled 011. The remaining product is a dark brown liquid which may be used as such or further purified. The reaction time may be shortened by raisingthe temperature, for example at a temperature of 260 C. a reaction time of 12 hours is suiiicient. It has also been found that increasing the amount of iodine shortens the time of-reaction, for example the use of 1000 grams of iodine allows a satisfactory reaction at 220 C. in about 12 hours. Instead of using iodine, hydrochloric acid may be used.

Example Be-Reaction product of acetone and phenyl beta naphthylamine: A mixture of 219 grams phenyl beta naphthylamine, 696 grams acetone and 10 grams of iodine are heated at approximately 210 to 220 C. during 33 hours. The pressure at this temperature is approximately 600 pounds per square inch. The crude reaction product is filteredthrough glass wool and the excess of acetone and the water formed during the reaction are removed by distillation.

Example C.-The reaction product of acetone and phenyl alpha-naphthyl-amine. This chemical is made according to the general procedure, namely by heating a mixture of 219 grams phenyl alpha naphthylamine, 116 grams of acetone, and 1.3 grams of iodine during 20 hours at approximately 210 to 220 C. The product which remains after removal of acetone and water is a free-flowing oil.

Other ketones than those mentioned that may be used are phorone, diethyl ketone, mono-chloracetone, dichloracetone, aldol-acetone, diacetyl, acetyleacetone, acetonyl acetone, diacetone alcohol, ethylidene-acetone, allyl-acetone, acetophenone, benzal acetone, furfural-acetone, salicyl aldehyde-acetone, cyelopentanone, cyclohexanone. Other secondary amino compounds than those mentioned that may be used are dinaphthyl amines, naphthyl amino diphenyl, carbazole, p-nitro diphenyl amine, 2,4 dinitro-diphenyl amine, p-amino-diphenylarnine, p-hydroxy-diphenylamine, sym-diphenyl-p-phenylene di- 100 amine, p-amino benzyl-aniline, p-amino pnaphthylamino diphenyl methane, sym-dinaphthyl-p-phenylene diamine, phenyl beta naphthyl guanidine, phenyl o-tolyl guanidine, di-o-tolyl biguanide, mono phenyl biguanide, diphenyl biguanide. Certain dehydrating agents have been mentioned as giving particularly effective results, but the invention generally is not to be limited thereto. Other dehydrating agents may be used such as calcium chloride, sulfanilic acid, phosphorus pentoxide, sodium hydroxide, magnesium perchlorate, acetic acid, barium oxide, zinc chloride, the amine addition product with zinc chloride such as (CeHsNHz), ZnClz, sulphuric acid, etc.

It is to be understood that the term aliphatic ketone includes both saturated and unsaturated aliphatic ketones of the open-chain and cycloaliphatic series, as well as hydroxyland halogen-substituted derivatives of such ketones, and ketones obtained by condensation of the foregoing with aldehydes andketones -and that the term also includes ketones comprising one aliphatic group and one aromatic group linked to the group.

It is further to be understood that the term secondary aromatic amino compound includes broadly any aromatic amino compound which comprises at least one secondary amino nitrogen atom linked to an aromatic nucleus.

The present invention is illustrated with a preferred embodiment as follows:

Example 1.-Beta naphthol derivative of the reaction product of acetone and diphenylamine: 20 grams of acetone-diphenyl amine condensation product and 20 grams of beta naphthol are warmed during 50 minutes at 80 C. After cooling, a solid product is obtained. The naphthol and the acetone-diphenylamine reaction product may be mixed in varying proportions. For instance, a second type is produced by heating grams of the same reaction product with 15 grams of beta-naphthol under the same conditions. Again a solid product is obtained. The exact nature of the combination is not known at present. When the second type was tested in a carbon black rubber stock in which diphenyl guanidine served as the accelerator it gave the following results:

+1 part of Green tensiles Blank the derivative 60' at 4712 4413 75 at 45# 4423 4237 Aged tensiles, 168 hrs. in oxygen at 45# 1546 3019 at 45# 1495 3357 Relative wear before aging 60 at 45# 132 125 75' at 45# 144 145 After aging 168 hrs. in oxygen 60' at 45# 71 104 75' at 45# 71 70 The first type when tested in a carbon black rubber stock using mercaptobenzothiazole as the accelerator gave the following results:

Green tensiles Blank ghgg gg Aged tensiles 216 hrs. in oxygen.... 1965 3210 Relative ugear before aging Relative wear after aging 216 hrs. in oxygen 96 132 The relative wear is a measure of resistance to abrasion.

Instead of beta-naphthol other naphthols such as alpha-naphthol and methylene-di-betanaphthol may be employed with analogous results.

The rubber may be treated with any single derivative or desired mixture of derivatives. Also in preparing the ketone-amine compounds, a mixture of ketones or a single ketone may be reacted with a single amino compound or with a mixture of amino compounds.

The invention may be used to retard the deterioration of inner tubes, tire treads, mechanical goods, footwear, rubber tiling stocks, latex and articles made from latex, etc. The term rubber is to be construed broadly as covering rubber in any form including natural rubber, synthetic rubber, gutta percha, balata, or other rubber-like materials.

With the detailed description given above, it will be obvious that modifications will suggest themselves, for example other accelerators and suitable compounding ingredients may be used in conjunction with the antioxidants,-all without departing from the principles of the invention, and it is not desired to limit the invention otherwise than as set forth in the appended claims.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. A process of treating rubber which comprises incorporating therewith the material resulting from combining a naphthol with the reaction product of an aliphatic ketone and a secondary aromatic amino compound.

2. A process of treating rubber which comprises vulcanizing rubber in the presence of the material resulting from combining a naphthol with the reaction product of an aliphatic ketone and a secondary aromatic amino compound.

3. A process of treating rubber which comprises incorporating therewith the material resulting from combining a naphthol with the reaction product of an aliphatic ketone and a secondary aromatic amine.

4. A process of treating rubber which comprises vulcanizing rubber in the presence of the material resulting from combining a naphthol with the reaction product of an aliphatic ketone and a secondary aromatic amine.

5. A process of treating rubber which comprises incorporating therewith the material resulting from combining a naphthol with the reaction product of an aliphatic ketone and a diarylamine.

6. A process of treating rubber which comprises vulcanizing rubber in the presence of the material resulting from combining a naphthol with the reaction product of an aliphatic ketone and a diarylamine.

7. A process of treating rubber which comprises incorporating therewith the material resulting from combining a naphthol with the reaction product of acetone and a diarylamine.

8. A process of treating rubber which comprises vulcanizing rubber in the presence of the material resulting from combining a naphthol with the reaction product of acetone and a diarylamine.

9. A process of treating rubber which comprises incorporating therewith the material resulting from combining beta naphthol with the reaction product of acetone and a diarylamine.

10. A process of treating rubber which comprises vulcanizing rubber in the presence of the material resulting from combining beta naphthol with the reaction product of acetone and. a diarylamine.

11. A process of treating rubber which comprises incorporating therewith the material resulting from combining beta naphthol with the reaction product of acetone and diphenylamine.

12. A process of treating rubber which comprises vulcanizing rubber in the presence of the material resulting from combining beta naphthol with the reaction product of acetone and diphenylaminc.

13. A rubber product resulting from the process set forth in claim 1.

14. A vulcanized rubber product obtained according to the process of claim 2.

15. A rubber product resulting from the process set forth in claim 11.

16. A vulcanized rubber product obtained according to the process of claim 12.

WILLIAM P. TER HORST. 

